Soil Stabilization, West Maui, Hawaii

Installed vegetative sediment traps. 11 were installed here, each estimated to capture one ton of sediment annually.

Project Summary

This project was developed to address threats to the coastal coral reefs in West Maui. Sediment destabilized by agricultural and recreational use eroding from slopes within the watershed flows into the reef, limiting sunlight in the water essential for survival of the coral. We worked with community leaders to develop project goals. With community volunteers we built sediment traps and used biochar to stabilize soils and protect the reef.

Problem
West Maui watersheds suffer from stressors to the nearshore reefs, including pollutants from legacy agriculture, increasing urban runoff, and wastewater injection wells that connect to the ocean.

Solution
Preventing erosion limits sediment transported downstream. The reef can be protected by working to stabilize soils on the slopes in the upper, middle, and lower watershed areas.

Implementation
Using bioengineering practices, we restabilized these areas for the long-term. Sediment traps were constructed using vetiver grass planting and rainwater drip irrigation. These sediment traps naturally hold soils on the slope and protect the reefs.
Outcomes
Stabilizing soils helps to mitigate the impacts from potential future land use changes. We will be able to transfer the methods developed here to other West Maui watersheds, including those held by private landowners and corporations.

Funders and Partners: Coral Reef Alliance, West Maui Kumuwai, Hawai’i Department of Land and Natural Resources, Maui County Parks and Recreation, local community volunteers and students from local high schools including Maui Preparatory School, West Maui Watershed Coordinator Tova Callender, Duane Sparkman and Ekolu Lindsey from Maui Cultural Lands, Chris Brosius from the Maui Mountain Watershed Partnership, Wesley Crile from Coral Reef Alliance, John Astilla from Sunshine Vetiver Solutions, Renee Ganske-Cerizo from Natural Resources Conservation Service (NRCS)